<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="author" content="wangbo">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /*  */
        @keyframes myscale {
            0%{transform: rotate(45deg)  scale(1);}
            20%{transform: rotate(45deg) scale(0.5);opacity: 0.5;}
            100%{transform: rotate(45deg)  scale(1);}
        }
        /* 页面内初始化,清除所有标签内外边距 */
        *{margin: 0;padding: 0;}
        div{width: 200px;height: 200px;}
        /* 子绝父相,子类绝对定位 */
        .fu{margin: 200px auto;background-color: red;position: relative;
        left: 0;top: 0;transform: rotate(45deg); 
        animation: myscale 2s infinite;
        }
        .zuo{position: absolute;left: -90px;top: 0;background-color: red; border-radius: 50%;}
        .you{position: absolute;left: 0;top: -90px;background-color: red;border-radius: 50%;}
        
    </style>
</head>
<body>
    <div class="fu">
        <div class="zuo"></div>        
        <div class="you"></div>
    </div>
    
</body>
</html>